<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>05-text-align</title>
    <style>
        div {
            width: 300px;
            height: 200px;
            background-color: #f00;
            text-align: center;
        }

        span {
            background-color: #00f;
        }

        strong {
            background-color: #0f0;
        }
    </style>
</head>
<body>

<div>
    <span>我是span</span>
    <strong>我是strong</strong>
</div>

</body>
</html>